Top Environmental Factors Contributing to Soil Erosion

There are also other renewable energy technologies that are still under development, including enhanced geothermal systems, concentrated solar power, cellulosic ethanol, piezoelectricity, and marine energy. These technologies are not yet widely demonstrated or have limited commercialization. Some may have potential comparable to other renewable energy technologies, but still depend on further breakthroughs. 

Enhanced geothermal systems (EGS) are a new type of geothermal power that does not require natural hot water reservoirs or steam to generate power. Most of the underground heat within drilling reach is trapped in solid rocks, not in water. EGS technologies use hydraulic fracturing to break apart these rocks and release the heat they contain, which is then harvested by pumping water into the ground. The process is sometimes known as “hot dry rock” (HDR). Unlike conventional geothermal energy extraction, EGS may be feasible anywhere in the world, depending on the cost of drilling. EGS projects have so far primarily been limited to demonstration plants, as the technology is capital-intensive due to the high cost of drilling

Sand battery

Sand batteries are large tanks filled with soapstone that absorb heat. Excess heat energy from renewable energy is piped into the tank, and the energy is then discharged as boiling water, steam, or heated air. Finland is using this technology in Pornainen, where Polar Night Energy built a 1MW sand battery capable of storing up to 100 MWh, which went online in 2025. 

Piezoelectricity

Piezoelectricity is the conversion of existing mechanical stress or vibration (classical mechanics) into an electrical charge without consuming or depleting a fuel source. Piezotronics enables the interaction of piezoelectric and semiconducting behaviors to modulate energy barriers at the contact surface, thereby controlling charge carrier transport. Since the introduction of nanogenerators, the efficiency of microscale energy harvesting has improved. For instance, nanogenerators typically consist of piezoelectric nanowires; as these wires bend or compress, the applied mechanical stress causes the ions within the material’s crystal lattice to shift their positions. 

This shift disrupts the nanowire’s charge symmetry, which causes an instantaneous charge polarization (separation of positive and negative charges) across the nanowire’s ends. Once polarized, electrons are freed from the attached electrode which generates usable alternating current (AC) electricity that can energize low-power sensors. Piezoelectric microelectromechanical systems (piezoMEMS), such as actuators for artificial organs and pacemakers or micropumps for drug delivery and reagent transfers, are vital for medical purposes and energy harvesting. Furthermore, specialized components like piezoelectric resonators and quartz crystal oscillators are used to regulate electrical circuit frequencies. 

Marine energy

Marine energy (also sometimes referred to as ocean energy) is the energy carried by ocean waves, tides, salinity, and ocean temperature differences. Technologies to harness the energy of moving water include wave power, marine current power, and tidal power. Reverse electrodialysis (RED) is a technology for generating electricity by mixing fresh water and salty seawater in large power cells. Most marine energy harvesting technologies are still at low technology readiness levels and are not used at large scales. Tidal energy is generally considered the most mature, but it has not seen wide deployment. The world’s largest tidal power station is on Sihwa Lake, South Korea, which produces around 550 gigawatt-hours of electricity per year. 

Earth’s infrared thermal radiation

Earth emits roughly 1017 W of infrared thermal radiation that flows toward the cold outer space. Solar energy hits the surface and atmosphere of the Earth and produces heat. Using various theorized devices like an emissive energy harvester (EEH) or thermoradiative diode, thisenergy flow can be converted into electricity. In theory, this technology can be used at night. Producing liquid fuels from oil-rich (fat-rich) varieties of algae is an ongoing research topic. Various microalgae grown in open or closed systems are being tried, including some systems that can be set up in brownfield and desert lands. 

Space-based solar power

There have been numerous proposals for space-based solar power, in which very large satellites with photovoltaic panels would be equipped with microwave transmitters to beam power back to terrestrial receivers. A 2024 study by the NASAOffice of Science and Technology Policy examined the concept and concluded that with current and near-future technologies, it would be economically uncompetitive.